Tetrafluoroethylene (C2F4, TFE, or FC-1114) is the monomer used to produce polytetrafluoroethylene (PTFE). TFE is highly explosive, flammable, and toxic. In order to prevent TFE from polymerizing unexpectedly while being stored, the TFE is inhibited with either hydrogen chloride (HCl) or carbon dioxide (CO2). TFE and CO2 have similar boiling points and also form an azeotrope, making a mixture of these components difficult if not impossible, to separate (see U.S. Pat. No. 5,345,013). Methods that are currently used for separating TFE from CO2 include membrane permeation, and caustic scrubbing. Following these procedures, the TFE-containing stream can then be processed, for example, to produce a fluoropolymer or copolymer, such as PTFE. The current processes for recovering TFE from CO2 suffer either from high variable cost (caustic scrubbing), high CO2 level in the product (membrane permeation), or multiple unit operations when additional steps are added to address the primary deficiencies.
An alternative approach to separating TFE from CO2 employs extractive distillation or absorption using at least one ionic liquid as an entrainer or absorbent, respectively. U.S. Provisional Application No. 60/719,735 describes the use of separation processes to separate components of mixtures, wherein said mixtures comprise at least one hydrofluorocarbon compound, and may additionally comprise a gas such as CO2. A need nevertheless remains for processes adapted specifically to the separation of TFE from CO2.